crypto/sha1: fix casting of d.nx in UnmarshalBinary
Fixes #29543
Change-Id: Ib7f3c32cc1e57c583ee52c486673a5b9568c2df8
GitHub-Last-Rev: 0cb3dc536245bb4f414cf09bb353fbafd5ca7537
GitHub-Pull-Request: golang/go#29544
Reviewed-on: https://go-review.googlesource.com/c/156279
Run-TryBot: Emmanuel Odeke <emm.odeke@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
diff --git a/src/crypto/sha1/sha1.go b/src/crypto/sha1/sha1.go
index db70b7d..8c48042 100644
--- a/src/crypto/sha1/sha1.go
+++ b/src/crypto/sha1/sha1.go
@@ -75,7 +75,7 @@
b, d.h[4] = consumeUint32(b)
b = b[copy(d.x[:], b):]
b, d.len = consumeUint64(b)
- d.nx = int(d.len) % chunk
+ d.nx = int(d.len % chunk)
return nil
}
diff --git a/src/crypto/sha1/sha1_test.go b/src/crypto/sha1/sha1_test.go
index 4f22926..c047204b 100644
--- a/src/crypto/sha1/sha1_test.go
+++ b/src/crypto/sha1/sha1_test.go
@@ -11,6 +11,7 @@
"crypto/rand"
"encoding"
"fmt"
+ "hash"
"io"
"testing"
)
@@ -152,6 +153,63 @@
}
}
+// Tests for unmarshaling hashes that have hashed a large amount of data
+// The initial hash generation is omitted from the test, because it takes a long time.
+// The test contains some already-generated states, and their expected sums
+// Tests a problem that is outlined in Github issue #29543
+// The problem is triggered when an amount of data has been hashed for which
+// the data length has a 1 in the 32nd bit. When casted to int, this changes
+// the sign of the value, and causes the modulus operation to return a
+// different result.
+type unmarshalTest struct {
+ state string
+ sum string
+}
+
+var largeUnmarshalTests = []unmarshalTest{
+ // Data length: 7_102_415_735
+ unmarshalTest{
+ state: "sha\x01\x13\xbc\xfe\x83\x8c\xbd\xdfP\x1f\xd8ڿ<\x9eji8t\xe1\xa5@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuv\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01\xa7VCw",
+ sum: "bc6245c9959cc33e1c2592e5c9ea9b5d0431246c",
+ },
+ // Data length: 6_565_544_823
+ unmarshalTest{
+ state: "sha\x01m;\x16\xa6R\xbe@\xa9nĈ\xf9S\x03\x00B\xc2\xdcv\xcf@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuv\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01\x87VCw",
+ sum: "8f2d1c0e4271768f35feb918bfe21ea1387a2072",
+ },
+}
+
+func safeSum(h hash.Hash) (sum []byte, err error) {
+ defer func() {
+ if r := recover(); r != nil {
+ err = fmt.Errorf("sum panic: %v", r)
+ }
+ }()
+
+ return h.Sum(nil), nil
+}
+
+func TestLargeHashes(t *testing.T) {
+ for i, test := range largeUnmarshalTests {
+
+ h := New()
+ if err := h.(encoding.BinaryUnmarshaler).UnmarshalBinary([]byte(test.state)); err != nil {
+ t.Errorf("test %d could not unmarshal: %v", i, err)
+ continue
+ }
+
+ sum, err := safeSum(h)
+ if err != nil {
+ t.Errorf("test %d could not sum: %v", i, err)
+ continue
+ }
+
+ if fmt.Sprintf("%x", sum) != test.sum {
+ t.Errorf("test %d sum mismatch: expect %s got %x", i, test.sum, sum)
+ }
+ }
+}
+
var bench = New()
var buf = make([]byte, 8192)
